For medical applications, administering particularized electrical energy to prescribed regions of the human body can achieve symptomatolytic effects for a variety of conditions, including chronic pain and certain motor disorders, or restore cardiac rhythms in heart tissue subject to fibrillation. Whether a stimulation lead is positioned in the brain, in the heart, along a peripheral nerve, or in the epidural space of a dorsal column, the positioning of the stimulation lead is critical to the effectiveness of subsequently delivered stimulation and prevention of undesirable, extraneous stimulation. Consequently, positioning a stimulation lead typically represents the most time intensive aspect of a stimulation lead implantation procedure.
To briefly describe a typical stimulation lead implantation procedure, a user first places a stimulation lead, whether through surgical intervention or otherwise, in the general region to be stimulated. Electrical energy is delivered through the stimulation lead, and a user guides the stimulation lead to a final placement position based on patient and/or physiological feedback. During this placement exercise, the stimulation lead is typically coupled to an electrical energy source, for example, an electrical pulse generator, through a temporary connector.
Conventional temporary connectors, at least in the field of spinal cord stimulation, are unfortunately not convenient to use. One such form of connector is the set screw-type connector.
Set screw connectors consist generally of a sleeve defining a longitudinal passage that receives the connector portion of a stimulation lead. The set screw connector has a plurality of "contacts" positioned along the length of the sleeve, each contact being formed of a removable set screw. The set screws span between an exterior surface of the sleeve and an interior surface of the sleeve and are adjustable so as to extend into, or retract from, the longitudinal passage.
Conventional stimulation leads can include four or more electrodes. As the set screws are quite small, understandably a user must be vigilant in initially loosening the set screws (i.e., to open the longitudinal passage of the connector) not allow a set screw to become free of the connector. Once a stimulation lead is positioned within the longitudinal passage, each set screw must be properly tightened to ensure contact with each contact of a received stimulation lead. Unless a torque wrench is used, care must be taken to limit the amount of force applied to each set screw to prevent damage to a received stimulation lead.
Some stimulation leads may include additional structure to aid in their steerability during placement. For stimulation leads that are introduced into a patient through a needle, for example, the stimulation lead may include an internalized stiffening wire to enhance the rigidity of the stimulation lead. As a further alternative, a stimulation lead may include a centralized passage to receive a steering mechanism, for example, a flexible stylet. The centralized passage opens at or near the proximal end of the stimulation lead to receive the flexible portion of a steering mechanism. Manipulation of the steering mechanism, as opposed to the stimulation lead or the connector, prevent inadvertent physical damage to the stimulation lead and/or connector.
In addition to the burden associated with tightening and loosening a plurality of set screws to engage/release a stimulation lead, known set screw-type connectors do not allow use of a flexible stylet when operatively engaged. Consequently, when positioning a stimulation lead having a stylet, a user is forced to either disregard the stylet or repeatedly connecting/disconnecting the stimulation lead between steps of positioning and applying electrical energy. In regard to the latter option, such task can be overwhelming when each connection/disconnection may require the management of a significant number of set screws.
Other connectors, for example, a cylindrical twist connector manufactured by Medtronic, Inc. for use with at least its Pisces.RTM. Quad stimulation leads, alleviate some of the burden in quickly establishing an electrical connection between the connector and the stimulation lead. Similar to the set screw-type connectors described above, however, the twist-type connectors also do not allow use of a flexible stylet when the stimulation lead is operatively engaged.
Accordingly, a first need exists for a connector that easily and quickly engages/releases at least a connector portion of a stimulation lead. A second need exists, whether in conjunction with such first need or otherwise, for a connector that provides access to a steering mechanism inlet of a stimulation lead when the connector engages the stimulation lead.